Undefined Variable Issue (super noob question)

[PeteSki]

Hi there, 

 

I'm just trying to get started with Houdini and I am stuck trying to follow a tute on attributes.

Can someone help me figure out why I'm getting this error in my copy node?

 

So I'm creating an attribute - "testattribute"

 

 

then I'm trying to stamp that attribute but I thats where I get this error...

 

 

Any ideas?

 

Thanks,

Pete

 

 

[papicrunch]

Hi 1nd welcome to houdini

you need to CAP your attribute : $TESTATTRIBUTE

you can see how is map your attribut by right clicking on a node and look under detail

Habe fun

Thomas

[pbarua]

And if you want to use lower case $testattribute then put testattribute in Local Variable field so it'll be mapped to testattribute. If you don't put anything there then it maps to upper case TESTATTRIBUTE by default.

Edited May 2, 2015 by pbarua

[PeteSki]

Hey thanks guys! Yeah I'm really getting into Houdini

But I'm stil stuck on this  

 

Capitalising didn't seem to change it. But if I middle click over the copy node (as below) it doesn't seem to have the test attribute within it... Maybe it's not making it past the scatter?

 

 

If anyone has a sec, here's the file. 

http://www.naffupdate.com/forumfiles/Paint%20Attributes%20Issue-e4lZk2Sloh.hiplc

 

Thanks!

Pete

[rtep]

You've made an attribute called testattribute but you need to map it to a variable.

Go to your attribute create node and in the local variable box type TESTATTRIBUTE

Leave the copy sop as you have it, $TESTATTRIBUTE.

 

It's called variable mapping.  It's confusing but basically it's a two part process, you have to create an attribute and then bind it to a local variable.

 

Any attribute you want to call in sops with the $ has to be variable mapped first.  After you add the local variable parameter you can middle click on the node and your mapped variables will be visible.

 

It's standard practice to to create an attribute all lowercase and then map it all capitalized. 

[rtep]

sorry if I'm just repeating other posts.  I know the varmapping confused me for awhile so I figured I'd try to give you as thorough an explanation as I could.

[Robert]

The problem is your variable mapping indeed. The variable mapping is done automatically in the attribcreate node but when you transfer the attribute to scattered points, the variable mapping is lost.

You can easily add this back with an attribwrangle node after your scatter with:

addvariablename(0,"testattribute","TESTATTRIBUTE");

[rtep]

You're right Robert.  I didn't think the attribute create automatically mapped new variables, I feel like I have to map my variables quite a lot, it must be different circumstances. 

 

Another way to do it PetSki is to copy/paste your attribute create after the scatter and disable the Write Values check box.  This tells the attribute create just to map an existing variable and not to change the values.  Same as the wrangle code above.